There have been proposed various fuel cell devices that generate power using hydrogen-containing gas and oxygen-containing gas as a next-generation energy source.
Such fuel cell devices are generally configured such that a fuel cell stack device made by combining a plurality of fuel cells is housed in a housing, and generate power by supplying a fuel gas (hydrogen-containing gas) to a fuel-side electrode of each fuel cell and supplying air (oxygen-containing gas) to an air-side electrode. In addition, the plurality of fuel cells are electrically connected to one another in series by a felt-like or plate-like current collecting member.
By the way, the above-mentioned current collecting member, a manifold configured to supply a reactant gas such as the fuel gas to the fuel cells, and the like generally employ an alloy that is easily processed and has heat resistance, and for example, an alloy containing 10 to 30 mass % of Cr has been used.
Here, when the current collecting member made of an alloy containing Cr is disposed between the fuel cells and the fuel cells are electrically connected to one another in series and power is generated for a long time, Cr contained in the current collecting member diffuses to the air-side electrode of the fuel cell and an interface between the air-side electrode and a solid electrolyte layer, resulting in an increase in electric resistance, so that the power generation performance of the fuel cell is degraded. This phenomenon is called Cr poisoning.
Here, in order to suppress such Cr poisoning, typically, a heat-resistant alloy made by coating the surface of a Cr-containing alloy with an oxide film of metal such as Mn, Fe, Co, or Ni is proposed (refer to Patent Literature 1).
In addition, a current collecting member made by coating a first layer that contains Zn and a second layer that contains a composite oxide having a perovskite structure containing La and Fe, or Mn, and an oxide of Zn in the surface of an alloy containing Cr is proposed (refer to Patent Literature 2).